1. Field of the Invention
The present invention relates generally to an inverter controlled generator apparatus, and more specifically to an inverter controlled generator apparatus to which control power source is supplied from outputs of a generator of its own.
2. Description of the Related Art
As a portable power source for outdoor use and an emergency power source, power source apparatuses of the type using an engine driven AC (alternating current) generator are known. A power source apparatus of this type produces an output in the manner that an AC current having been output from an engine-driven generator is converted into a DC (direct current) current. Then, the DC current is converted by an inverter into an AC current having a predetermined frequency such as a commercial frequency, and the AC current is output. In the power source unit of this type, the power source for driving the inverter is supplied from an output of a generator that is driven by an engine. As such, at an initial stage after the start of the engine, the engine revolution speed is low, and hence the output of the generator is not sufficient, so that the power source voltage of the inverter-driving power source is likely to become unstable.
In power source units of the type described above, control itself or the like for maintaining a generation output voltage to be stable by way of analog control in many cases on the one hand, and in many cases, an inverter-driving signal system, engine control, and the like use a microcomputer to perform digital control on the other. This requires the use of, for example, power sources for the digital control, analog control, and power sources for each of a voltage specification, thereby making the power source system to tend to be complex.
For example, according to a generator disclosed in Japanese Unexamined Patent Application Publication No. 06-121597, a power source for a controller is obtained from a transformer secondary output of a primary winding or an auxiliary winding. The generator is designed such that the power source can be secured in the state that the revolution speed range is as low as possible; and taking into account the characteristic of increasing voltage in association with increase in revolution speed, the generator is designed to use a voltage doubling rectification method to implement loss suppression.
In the above-described generator using the voltage doubling rectification method, the transformer output from the winding undergoes voltage doubling rectification, and the power source is formed to use both polarities on the negative and positive sides. As such, in terms of circuit configuration, when setting a power source for a microcomputer to the negative power source, it is difficult to produce the output voltage with high accuracy, thereby creating the cause of increasing nonuniformity of the voltage.
In addition, when an engine-speed controlling electronic governor is mounted, an inverter-controlling power source cannot be secured, so that the electronic governor cannot be started and actuated from a low engine revolution speed range. To enable the electronic governor to be started and operated from the low engine revolution speed range, the number of turns of a power-source dedicated winding or transformer's secondary winding provided in the generator may be increased to increase the voltage. However, this involves an increase in loss in a high revolution speed range and, requires increase in the voltage resistance of a power-source IC.
The situation is similar even in a generator that has a battery as a power source. Even with a battery being provided, engine-driven generator apparatuses are of a portable type or are for emergency use in many cases, so that when the battery is used up, the engine needs to be manually started by using, for example, a recoil starter. As such, the same situation as that in a generator not having a battery needs to be contemplated.